Receiver for wireless telegraphy



(kit. 30 1923. 1,472,92

H. J. ROUND RECEIVER FOR WIRELESS TELEGRAPHY Filed Jul 9, 1921 gwvamboz H. J. ROUND W WOX W Patented @et 30, E923.

untrue stares mariner PATENT cruise.

HENRY JOSWE BOUND, OF LONDON, ENGLAND, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE.

' RECEIVER FOR WIRELESS TELEGRAPHY.

Application filed July 9, 1921. Serial No. 483,493.

(eaanrnn mar. run raovrsroue or run ACT or u'aacu a, 1921, 41 srar. n, 1313.

To all whom it may concern: I

Be it known that I, HENRY Josnrn Room), a British su elect, of Marconi House, Strand, London, W.- England, have made certain new and useful Improvements in Beceivers for Wireless Telegraphy (for WhlCll I have filed applications in Great Britain,,-

Nov. 28, 1913, Patent No. 27,480 0151913; Belgium Jul 5, 1920; F rancei'zlluly 1, 1920; Japan, J ulyi, 1920; Poland, Jul '8, 1920; Canada, Jul 10, 1920; Brazil, Ju y 2, 1920; Germany, une 22, 1920; New Zealand, June 22 1920; Trinidad, May 31, 1920; India, July 9, 1920; Australia, June 15, 1920; Ceylon, June 2, 1920; Italy,- June 7, 1920; Portugal, May 18, 1920 Tobaga, May 31, 1920), of which the following is a specification.

This invention relates to improvements in receivers for wireless telegraphy and has for its object the elimination of atmospherlcs.

It is well known that an atmospheric, being highly damped, causes the receiving circuits to oscillate at their own natural frequency and cannot therefore be eliminated by tuning these circults. It 1s also well known that if an oscillatory potential of a certain frequency be induced in an oscillatory circuit of a different natural frequency two sets of oscillatlons are produced in that circuit, namely a transient free oscillatioii of the natural frequency of the circuit and a forced oscillation of the fre-. quency of the induced potential, the latter oscillation being transient if this potential is caused by damped waves and permanent, if it is caused by undamped or continuous waves.

According to the present invention I make the natural frequency of the receiving aerial different from that of the received waves so that both the forced and the free oscillations occur producing the well known phenomenon of beats and I rectify the resultant current and carry it to a circuit tuned to the beat frequency and I may directly.

bility it is necessary to employ one of the well known devices for causing these beats to produce audible indications as for example a rectifier, or in the case of continuous waves a ticker or the generation of an other frequenc which will interfere with the inaudible requency and produce beats of an audible frequency.

' Where such a device is used for receiving continuous or nearly continuous waves, it is obvious that the transient free oscillations of the aerial will notv produce'effective beats with the continuing forced oscillations, and in such cases it is desirable to generate a continuous oscillation of a frequency which is different from that of the forced oscillations and may be equal to the natural frequenc of the aerial. These locally produced osci lations will interferewith the forced oscillations and produce the required beat frequency, while they either will not intera condition of saturation so that the'oscilla-,

In Figure 1, A is the aerial slightly out of tune with the incoming signal waves. B is 'a circuit which is coupled to the aerial and which is preferably aperiodic. D is a circuit connected to the circuit B through a rectifying crystal C and tuned to the frequency of the beats due to the forced and free oscillations and T is a telephone inductively coupled to the circuit D.

With such a simple arrangement however it may be difficult to get the beat frequency unaffected by atmospherics and yet low enough to be within the limits of audibility and to obviate this difliculty I ma employ the arrangement illustrated in igure 2. A B C, D are the same as before but D is now coupled throu h an intermediate circuit E to a circuit 1 in which oscillations can be induced by means of a local oscillation circuit F of such a frequency as to interfere with the oscillations in D producing beats of a frequency within the limits of audibility. The circuit B is connected through a second rectifier Q to a circuit D connected to a telephone.

Figure 3 is similar to Figure 1 except that -a local oscillation circuit F is provided for eneratin continuous oscillators in B for inter ering with the forced oscillations in the aerial when continuous oscillations are employed for signalling. The frequency of the oscillations induced in circuit D by circuit F may be equal to the natural frequency of the aerial.

Having described my invention, what I claim is:

1. In a receiver for wireless telegraphy the combination of an aerial slightly out of tune with the signal waves, means for rectifying the resultant current due to the forced and free oscillations in the aerial and a circuit tuned to the beat frequency.

2. In a receiver for wireless telegraphy the combination of an aerial slightly out of tune with the signal waves, a circuit coupled to the aerial, means for generating in that circuit oscillations of a frequency slightly different from that of the signal waves, means for rectifying the resultant current and a circuit tuned to the beat frequency.

3. A method of eliminatin the results of atmospherics in wireless te egraph receivers, which consists in the production by oscillations having slightly different frequencies of beats having widely different frequencies.

4. A method of eliminating the results of atmospherics in wireless telegraph receivers which consists in the production of a frequency interfering with the received frequency, rectifying, inducing a frequency interfering with the resultant oscillations and rectif ing again.

5. n a radio receiving system, the combination of an aerial sllghtly out of tune with the signal waves, a receiving circuit coupled thereto, a circuit tuned to a frequency equalling the difference between the aerial frequency and the signal fre uency, and rectifyin means between said circuits.

6. In a ra io receiving system, the combination of an aerial slightly out of tune with the signal waves, a receiving circuit coupled thereto, a circuit tuned to a frequency equalling the difierence between the aerial frequency and the signal frequency, rectifying means between said circuits and indicatin means" associated with the last mentione circuit.

7. In a radio receiving system, the combination'of high frequency circuits comprising an aerial-slightly out of tune with the signal-waves, a receiving circuit coupled thereto, a source of local oscillations coupled to the high frequency circuits, a low 7 frequency circuit tuned to a frequency equalling the difference between the aerial frequency and the signal fre uency, and rectifying means between sai receiving circuit and said low frequency circuit.

8. In a radio receiving system the combination of hi h fre uency circuits comprising an aeria slight y out of tune with the signal waves, a receivingcircuit coupled thereto, a source of local oscillations coupled to the high frequency circuits, a low frequency circuit tuned to a frequency equallmg the difference between the aerial freuency and the signal frequency, and rectiying means between said recelvmg circuit and said low frequency circuit.

9. In a radio receiving signal system, the combination of high frequency circuits comprising an aerial slightly out of tune with the signal waves, a receiving circuit coupled thereto, a source of local oscillations coupled to the high frequency circuits of the same order of magnitude as the frequency of high frequency circuits, a low frequency circuit tuned to a frequency equalling the difference between the aerial frequency and the signal frequency and rectifying means between said receiving circuit and said low frequency circuit.

10. In a radioreceiving signal system, the combination of high frequency circuits comprising an aerial slightly out of tune with the signal waves, a receiving circuit coupled thereto, a source of local oscillations coupled to the hi h frequency circuit having a frequency su stantially equal to the aerial fregpency, a low frequency circuit tuned to a equency equalling the difierence between the aerial frequency and the signal fre uency and rectifying means between sai receiving circuit and said low frequency circuit.

11. A method of eliminating atmospheric interference in radio rece tion which consists in causing the sai signal and at- 120 mospheric efiects to produce oscillations of two different frequencies, superimposin alocal frequency on said oscillations of .a requency adapted to produce beats of different frequencies therewith and selectin the 125 beat fre uency produced between the signal and the ocal oscillations.

12. A method of eliminating atmospheric interference in radio signaling which consists in slightly detuning the aerial to cause 130 the signal and atmospheric effects to produce oscillations of two slightly different frequencies, superimposing a local frequency on said oscillations of a frequency adapted to produce beats with said oscillations of different frequencies and selecting the beat due to the signal and local oscillation.

13. A method of receiving radio si als which consists in causing the receive effects to produce oscillations of two different frequencies, rectifying the beats between said oscillations, superimposing a local frequency on the resultant beat frequency and rectifying again.

14. A method of receiving radio signals which consists in causing the received ef fects to produce oscillations of two different frequencies differing from each other so as to produce inaudible beats, rectifying the beats between said oscillations, superimposing a local frequency on said inaudible beats ada ted to produce therewith an audible beat re uency and rectifying again.

l-IENRY JOSEPH ROUND. 

